CA1126320A - Self-converging deflection units for colour display tubes of different screen formats - Google Patents
Self-converging deflection units for colour display tubes of different screen formatsInfo
- Publication number
- CA1126320A CA1126320A CA333,922A CA333922A CA1126320A CA 1126320 A CA1126320 A CA 1126320A CA 333922 A CA333922 A CA 333922A CA 1126320 A CA1126320 A CA 1126320A
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- CA
- Canada
- Prior art keywords
- deflection
- coil
- display tube
- display
- screen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 claims abstract description 7
- 238000010894 electron beam technology Methods 0.000 claims description 24
- 239000003302 ferromagnetic material Substances 0.000 claims description 6
- 230000003247 decreasing effect Effects 0.000 claims description 4
- 230000007423 decrease Effects 0.000 claims 1
- 235000019571 color Nutrition 0.000 abstract description 2
- 201000009310 astigmatism Diseases 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 230000006978 adaptation Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910001369 Brass Inorganic materials 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 239000010951 brass Substances 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000005291 magnetic effect Effects 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 240000006829 Ficus sundaica Species 0.000 description 1
- BDAGIHXWWSANSR-UHFFFAOYSA-M Formate Chemical compound [O-]C=O BDAGIHXWWSANSR-UHFFFAOYSA-M 0.000 description 1
- 240000000136 Scabiosa atropurpurea Species 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
- H01J29/70—Arrangements for deflecting ray or beam
- H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
- H01J29/76—Deflecting by magnetic fields only
- H01J29/762—Deflecting by magnetic fields only using saddle coils or printed windings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2229/00—Details of cathode ray tubes or electron beam tubes
- H01J2229/70—Electron beam control outside the vessel
- H01J2229/703—Electron beam control outside the vessel by magnetic fields
- H01J2229/7031—Cores for field producing elements, e.g. ferrite
Landscapes
- Video Image Reproduction Devices For Color Tv Systems (AREA)
- Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
- Details Of Television Scanning (AREA)
- Looms (AREA)
Abstract
ABSTRACT:
A method of composing self-converging deflection units for colour display tubes of the in-line type having the same deflection angles and neck diameters but different screen formats, in which for all screen formats one and the same design of the deflection unit is used, which deflect-ion unit is self-converging for a colour display tube of a given screen format and is made self-converging for a col-our display tube of a different screen format by varying the effective lengths of the line and field deflection coils constructed as saddle-shaped coils of the shell type in opposite senses with the position of their front ends remaining the same.
A method of composing self-converging deflection units for colour display tubes of the in-line type having the same deflection angles and neck diameters but different screen formats, in which for all screen formats one and the same design of the deflection unit is used, which deflect-ion unit is self-converging for a colour display tube of a given screen format and is made self-converging for a col-our display tube of a different screen format by varying the effective lengths of the line and field deflection coils constructed as saddle-shaped coils of the shell type in opposite senses with the position of their front ends remaining the same.
Description
llZ~i3%0 The invention relates to a series of at least two electro-magnetic deflection units for colour display tubes of the in-line type having the same deflection angles and neck diameters but at least two different screen formats, in which each deflection unit is provided with:
a first deflection coil having a front end and a rear end for deflecting electron beams generated in the dis-play tube in a vertical direction, the electron beams, when the deflection unit has been mounted on a display tube, passing through the coil in the direction from the rear end towards the front end, as well as a second deflection coil, which coil is of the saddle type and also has a front end and a rear end, for deflecting electron beams generated in the display tube in a horizontal direction, a yoke ring of ferromagnetic material being provided around the at least the second deflection coil.
For some time a colour display tube has become the vogue in which three electron beams are used in one plane; the type of such a cathode ray tube is sometimes referred to as "in-line". In this case, for decreasing con-vergence errors of the electron beams, a deflection unit is used having a line deflection coil which, for deflecting the electron beams in a horizontal direction, generates a pin-cushion field, and a field deflection coil which, for deflecting the electron beams in a vertical direction, gen-erates a barrel-shaped field. Within the scope of the invention, such a deflection unit may comprise in partic-ular the combination of a field deflection coil of the so-called saddle shell type with a line deflection coil of the l~LZ63Z~
so-called saddle shell type. A coil of the saddle type is to be understood to mean herein a coil which is constructed from two coil halves, the front and rear ends of each coil half extending approximately perpendicularly to the plane in which the electron beams lie, and a coil of the saddle shell type is to be understood to mean herein a coil which is constructed from two coil halves in which the front end of each coil half extends approximately perpendicularly to the plane in which the electron beams lie, and the - cylin-drical - rear end is adapted to the outer surface of the neck part of the display tube.
Deflection units for in-line colour display tube systems can in principle be made to be entirely self-con-vergent, that is to say in a design of the deflection unit which ensures convergence of the three electron beams on the axes, anisotropic y-astigmatism errors, if any, can simul-taneously be made zero in the corners without this requiring extra correction means. Where it would be interesting from a point of view of manufacture to have a deflection unit which is self-converging for a series of display tubes of the same deflection angles and neck diameters but different screen formats, the problem exists, however, that a deflec-tion unit of given main dimensions can be used only for display tubes of one screen format. This means that only one screen format can be found for a fixed maximum deflec-tion angle in which a given deflection unit is self-converg-ing without a compromise (for example, the use of extra correction means).
It is the object of the invention to provide a method of the kind mentioned in the opening paragraph with g llZ63~) which it is possible, starting from deflection coils having given main dimensions, to compose self-converging deflec-tion units for a series of display tubes of different screen formats.
Within the scope of the invention this object is achieved in that for a given screen format the first and the second coil each have a given effective length between their front and rear ends, the effective length of the first coil being larger and for the effective length of the second coil being smaller for a larger screen format, and conver-sely, so as to provide for different screen formats a self-converging combination of display tube/deflection unit.
The invention is based on the recognition of the fact that, if self-convergence on the axes has been reached, the possibly remaining anisotropic _-astigmatism error (the so-called ~-convergence error in the corners) mainly depends on the distance between the line deflection point and the field deflection point and to a much smaller extent on the main dimensions and the shape of the deflection coils used.
Now if deflection units for different screen formats are to be composed while using deflection coils having the same shape and main dimensions, the distance between the line and field deflection points may be used as a parameter to never-theless achieve self-convergence for a family of display tubes having different screen formats but the same maximum deflection angles.
Within the scope of the invention, the variation in the distance between the line and field deflection points necessary for adapting to different screen formats is achieved by increasing or decreasing the effective coil llZ63Z~:) length of either the line coil or the field coil, or of both but then in the opposite sense, with the main dimensions of the deflection coils remaining the same and with the dimen-sions of the yoke ring remaining the same, for example, by mechanically making the coil or coils on the rear side smaller and longer, respectively, by a few millimetres, or by positioning, with the coil length remaining the same, the window farther or less far to the rear (so that the turns on the rear side are more or less compressed). As will be explained hereinafter, all this can be carried out very simply in practice when saddle-shaped coil halves of the shell type are used at least for the line coil and prefer-ably also for the field coil.
The invention actually involves that, for use of a deflection unit in a display tube having a larger screen format than the display tube for which it is designed, the deflection points of the line deflection field and field deflection field generated by the given deflection unit must be moved apart and, for use in a display tube having a smaller screen format, they must be moved towards each other.
The use of the invention results in particular in a series of at least two combinations display tube/deflect-ion unit, the display tubes having the same neck diameters and deflection angles but different screen formats, each deflector unit comprising: ;
a first deflection coil of the saddle type having a front end and a rear end for deflecting electron beams generated in the display tube in a vertical direction, the electron beams, when the deflection unit has been mounted on 11;~t~3~:0 a display tube, passing through the coil in the direction from the rear end towards the front end:
a second deflection coil of the saddle type also having a front end and a rear end for deflecting electron beams generated in the display tube in a horizontal direc-tion, as well as a yoke ring of ferromagnetic material sur-rounding the two deflection coils, which series is charact-erized in that the first and second deflection coils at their front ends have a cup-shaped portion which is adapted to the outer surface of the display tube, and at their rear ends have a cylindrical portion which is adapted to the sur-face of the display tube on the one hand the dimensions and the shape of the cup-shaped portion of the first deflection coils and on the other hand the shape and the dimensions of the cup-shaped portion of the second deflection coils in display tubes of different screen formats being the same, the effective length of the cylindrical portion of the first coil increasing and that of the second deflection coil decreasing when the screen format of the display tube for which they are mounted increases, and conversely.
(An example of a series of display tubes is, for example, a series having a constant deflection angle of 100 and 20, 22 and 26 inch screens).
As will be described in greater detail hereinafter with reference to the method of the invention, the great advantage of the invention is that for adaptation to the various screen formats of a given series, only a very small alteration in the length of the ~cylindrical) rear section of the individual deflection coils is necessary to obtain the desired variation in the distance between the deflection 63~
points. This means that the complicated cup-shaped portion may remain unvaried as regards dimensions so that self-con-verging deflection coils for display tubes of different screen formats can be made by means of one jig (having an adjustable rear section). In order to maintain convergence on the axes, the wire distribution in the cup-shaped portion of the coils needs at most only small alterations and in ; fact this applies only to the line coil. The main geometry, however, remains unchanged.
The invention therefore also relates to a method of assembling electromagnetic deflection units for colour display tubes of the in-line type having the same deflection angles and neck diameters but at least two different screen formats in which a first deflection coil of the saddle type having a front end and a rear end, a cup-shaped portion at the front end and a cylindrical portion at the rear end, for deflecting electron beams generated in the display tube in a vertical direction, the electron beams, when the deflection unit has been mounted on a display tube, passing through the coil in the direction from the rear end towards the front end, is combined with a second deflection coil, which coil ' is of the saddle type and has a front end and a rear end, a cup-shaped portion at its front end and a cylindrical por-tion at its rear end, for deflecting electron beams gener-ated in the display tube in a horizontal direction, a yoke ring of ferromagnetic material being provided around the assembly of the two deflection coils, characterized in that at least the second deflection coil is composed of two iden-tical halves which are wound on a jig having a cup-shaped portion and a cylindrical portion. The shape and the dimen-1~63Z`O
sions of the cup-shaped portion being the same for each screen format, the cylindrical portion of the jig, however, having an adjustable body for determining the length of the cylindrical portion of the coil halves.
A variation A D in the distance between line and field deflection point is produced by varying the effective length of the line coil with respect to that of the field coil. ~ D is linearly associated with the variation of the screen format, in which the relation applies that:
f~ D = ~ ~ Zs' where ~ Zs is the variation in the distance from the front end of the coil situated nearest to the screen (this gener-ally is the line coil) to the screen. The value of ~ is roughly between 0.05 and 0.15.
Embodiments of the invention will now be described in greater detail, by way of example, with reference to the accompanying drawing, in which:
Fig. 1 shows diagrammatically a colour display tube having a deflection unit;
Fig. 2 shows diagrammatically a deflection unit according to the invention suitable for a colour display tube having a first screen format;
Fig. 3 shows diagrammatically the same deflection unit as in Fig. 2 but now adapted to a colour display tube of a second screen format:
Fig. 4 shows diagrammatically a jig to be used in the method according to the invention and having an adjust-able rear section;
Fig. 5 is a side-elevation of a field coil half as used in the deflection unit shown in Fig. 2;
~r ~63;~
Fig. 6 is a side elevation of a field coil half as used in the deflection unit shown in Fig. 3;
Fig. 7 shows the magnetic fields generated in the axial direction by the deflection unit shown in Fig. 2;
Fig. 8 shows the magnetic fields generated in the axial direction by the deflection unit shown in Fig. 3.
Fig. 1 is a diagrammatic sectional view of a col-our display tube 1 of the in-line type having a display screen 2, a tube neck 3 and three electron guns 4 situated in one plane. A deflection unit 5 connected to the display tube comprises a rotationally symmetric yoke ring 6, a saddle coil 7 of the shell type for the horizontal deflection (the so-called line coil) and a saddle coil 8 of the shell type for the vertical deflection (the so-called field coil).
It has been found that, starting from a given main geometry of line and field coil, the variation of the effec- ;
tive lengths of the line coil and the field coil with res-pect to each other is a very helpful parameter to adjust the third order anisotropic astigmatism. The correction of the third order anisotropic astigmatism by mutual shifting of the deflection points is roughly ten times faster than by shifting the deflection unit as a whole.
It has so far geen generally believed that also in the construction of in-line deflection systems it was not allowed to deviate from the requirement accepted in the con-struction of delta deflection systems that line and field - deflection centres should coincide and should remain coin-ciding upon deflection. As will be explained hereinafter, the invention is based on the fact that in a deflection unit of the in-line type destined for use in combination with ~1;263~0 picture tubes having an tuninterrupted) line structure of the phosphors, the location of line and field deflection centres can just be optimalised in behalf of convergence and raster performance.
Of late years a development has occurred in colour television display systems which may be characterized by:
- the change of the delta arrangement of electron guns into an in-line arrangement in which the associated deflection system has been developed from non-self-converg-ing to self-converging;
- the change of the hexagonal mask structure of the display tube in to a line structure.
Where such a system must satisfy requirements as regards convergence, raster shape and purity (colour purity, landing reserve), requirements may be derived which each of : the components of said system should satisfy (think, for example, of the specific wire distribution for self-conver-gence).
Where purity is concerned, the general situation is that a deflection unit is given (which satisfies certain requirements as regards convergence, raster and shifting space), it being one of the responsibilities of the display tube designers to develop such an analogon of the electron-optical properties of said deflection unit that during the manufacture of the display screen the exposure optics ensure that the (visual) exposure "centre" and the deflection "centre" will afterwards coincide.
Because for a delta-gun arrangement coupled to a non-self-converging deflection unit the triodistortion (and the variation in deflection point~, upon deflection, results _ g _ 112~i3~
already in conflicting requirements to be imposed upon the exposure optics, a generally accepted requirement imposed from purity on the properties of the deflection unit is that in a delta system:
line and field deflection points should coincide and should go on coinciding upon deflection.
In in-line self-converging colour television dis-play systems the variation in deflection point of line and field coil is already so different in character that it was deemed necessary to abandon the hexagonal mask structure which was substantially ideal as regards purity properties t and to proceed to a line structure. Said line structure is characterized by a phosphor line which is uninterrupted in the field direction (which, with invisibility requirements imposed upon the mask structure remaining the same, has half the width of the original round phosphor dot).
These phosphor lines which are uninterrupted in the direction of the picture has the favourable result that in this direction in principle no mislanding (= not landing of a beam on a dot of its own coiour) can occur.
As a result of this, the differing variation in deflection point of the field coil with respect to the line coil can easily be permitted.
In that case it is in principle of no importance any longer for purity whether line and field deflection points will coincide also in the case of a deflection over a very small angle.
In other words, the generally accepted requirement in a delta system that in a deflection unit line and field deflection points will coincide and will go on coinciding ~.~;263~
upon deflection may be omitted in an in-line system when the hexagonal mask structure in the display tube is replaced by a line mask structure. (N.B.: so this is not a result of the in-line arrangement of the electron guns in themselves).
Within the scope of the invention this is used in the adaptation of the deflection unit 5 to a display tube having a screen 2' of a screen format different from that of the display screen 2 (in this case larger) but of equal deflection angle and neck diameter.
How this adaptation works is shown in more detail - in Figs. 2, 3, 4, 5 and 6.
Fig. 2 is a side elevation of the part of a deflection unit 9 situated above the tube axis and provided on a display tube 10. Deflection unit 9 comprises a line coil 11 having a front end 12 situated at a distance Zs from the display screen 13, and a field coil 14. In order that the deflection unit 9 be self-converging on the display tube lO (for example, a 110 tube having a 20 inch screen), the end 16 of the field deflection coil 14, as well as the end 15 of the line deflection coil 12 has a given length. The distance between the rear end 15 of the line deflection coil 12 and the rear end 16 of the field deflection coil 14 is denoted by S.
Fig. 3 shows a modified deflection unit 9', in this case the part situated below the tube axis, and shows that the distance S is changed into the distance S' where S' - S = S, by varying the lengths of the parts of the coils extending parallel to the tube axis. The deflection unit 9' is now self-converging on a display tube 17 having a second (larger) screen format (for example, a 110 tube hav-~i263~) P~ 9206 ing a 22 inch screen). In the present case the field deflec-tion coil 14 has for this purpose been extended on its rear side by approximately 5 mms and the line deflection coil 12' has been shortened on its rear side by approximately 5 mms, while the screen format is changed by 2 inches, which is shown in Fig. 3 by the distance ~ Zs by which the distance from the front end of the line deflection coil 12' to the display screen 18 has been increased from Zs to Zs' Changing the length of, for example, the field deflection coil is realised by means of a jig 19 which is shown in Fig. 4 diagrammatically partly as a plan view and partly as a sectional view. It consists of a (brass)lower jig 20 and a (brass) upper jig 21 which are separated from each other by a winding slot 22 where a winding wire is insorted. Holes to shoot pins into the rear end of a coil have been made in a cylindrical portion 23 which is screwed to the upper jig 21. One of these holes is denoted by 24.
These pins together with an exchangeable window block 25 screwed to the lower jig 20 determine the place where the copper wires bend on the rear side of the coil and hence determine the length of the deflection coil.
By placing a cylindrical auxiliary plate 26 of the required thickness between the upper ~ig 21 and the cylind-rical component 23 and simultaneously adapting the window block 25 as regards length, the jig can simply be made suit-able for winding another coil from the same family. The profiled member on the cup side which is difficult to manu-facture is not changed. Dies and winding wings need not be varied either. Preferably the lengths of the line and field deflection coils are varied in the opposite sense when ;
.~
~1~63~0 changing to another format, so that the differences between the coils from the whole family do not become too large (see also Fig. 2, 3).
Fig. 5 is a plan view of one half of the field deflection coil 27 and Fig. 6 is a plan view of one half of the field deflection coil 28 having an elongated rear end manufactured in the above-described manner.
By varying the distance between the rear ends of the line and field deflection coils, the distance between the line and field deflection point is varied and hence a deflection unit is obtained which is self-converging for another screen format. This is explained in Figs. 7 and 8.
A field deflection field HB and a line deflection field HL
are generated by means of a deflection unit as shown in Fig.
a first deflection coil having a front end and a rear end for deflecting electron beams generated in the dis-play tube in a vertical direction, the electron beams, when the deflection unit has been mounted on a display tube, passing through the coil in the direction from the rear end towards the front end, as well as a second deflection coil, which coil is of the saddle type and also has a front end and a rear end, for deflecting electron beams generated in the display tube in a horizontal direction, a yoke ring of ferromagnetic material being provided around the at least the second deflection coil.
For some time a colour display tube has become the vogue in which three electron beams are used in one plane; the type of such a cathode ray tube is sometimes referred to as "in-line". In this case, for decreasing con-vergence errors of the electron beams, a deflection unit is used having a line deflection coil which, for deflecting the electron beams in a horizontal direction, generates a pin-cushion field, and a field deflection coil which, for deflecting the electron beams in a vertical direction, gen-erates a barrel-shaped field. Within the scope of the invention, such a deflection unit may comprise in partic-ular the combination of a field deflection coil of the so-called saddle shell type with a line deflection coil of the l~LZ63Z~
so-called saddle shell type. A coil of the saddle type is to be understood to mean herein a coil which is constructed from two coil halves, the front and rear ends of each coil half extending approximately perpendicularly to the plane in which the electron beams lie, and a coil of the saddle shell type is to be understood to mean herein a coil which is constructed from two coil halves in which the front end of each coil half extends approximately perpendicularly to the plane in which the electron beams lie, and the - cylin-drical - rear end is adapted to the outer surface of the neck part of the display tube.
Deflection units for in-line colour display tube systems can in principle be made to be entirely self-con-vergent, that is to say in a design of the deflection unit which ensures convergence of the three electron beams on the axes, anisotropic y-astigmatism errors, if any, can simul-taneously be made zero in the corners without this requiring extra correction means. Where it would be interesting from a point of view of manufacture to have a deflection unit which is self-converging for a series of display tubes of the same deflection angles and neck diameters but different screen formats, the problem exists, however, that a deflec-tion unit of given main dimensions can be used only for display tubes of one screen format. This means that only one screen format can be found for a fixed maximum deflec-tion angle in which a given deflection unit is self-converg-ing without a compromise (for example, the use of extra correction means).
It is the object of the invention to provide a method of the kind mentioned in the opening paragraph with g llZ63~) which it is possible, starting from deflection coils having given main dimensions, to compose self-converging deflec-tion units for a series of display tubes of different screen formats.
Within the scope of the invention this object is achieved in that for a given screen format the first and the second coil each have a given effective length between their front and rear ends, the effective length of the first coil being larger and for the effective length of the second coil being smaller for a larger screen format, and conver-sely, so as to provide for different screen formats a self-converging combination of display tube/deflection unit.
The invention is based on the recognition of the fact that, if self-convergence on the axes has been reached, the possibly remaining anisotropic _-astigmatism error (the so-called ~-convergence error in the corners) mainly depends on the distance between the line deflection point and the field deflection point and to a much smaller extent on the main dimensions and the shape of the deflection coils used.
Now if deflection units for different screen formats are to be composed while using deflection coils having the same shape and main dimensions, the distance between the line and field deflection points may be used as a parameter to never-theless achieve self-convergence for a family of display tubes having different screen formats but the same maximum deflection angles.
Within the scope of the invention, the variation in the distance between the line and field deflection points necessary for adapting to different screen formats is achieved by increasing or decreasing the effective coil llZ63Z~:) length of either the line coil or the field coil, or of both but then in the opposite sense, with the main dimensions of the deflection coils remaining the same and with the dimen-sions of the yoke ring remaining the same, for example, by mechanically making the coil or coils on the rear side smaller and longer, respectively, by a few millimetres, or by positioning, with the coil length remaining the same, the window farther or less far to the rear (so that the turns on the rear side are more or less compressed). As will be explained hereinafter, all this can be carried out very simply in practice when saddle-shaped coil halves of the shell type are used at least for the line coil and prefer-ably also for the field coil.
The invention actually involves that, for use of a deflection unit in a display tube having a larger screen format than the display tube for which it is designed, the deflection points of the line deflection field and field deflection field generated by the given deflection unit must be moved apart and, for use in a display tube having a smaller screen format, they must be moved towards each other.
The use of the invention results in particular in a series of at least two combinations display tube/deflect-ion unit, the display tubes having the same neck diameters and deflection angles but different screen formats, each deflector unit comprising: ;
a first deflection coil of the saddle type having a front end and a rear end for deflecting electron beams generated in the display tube in a vertical direction, the electron beams, when the deflection unit has been mounted on 11;~t~3~:0 a display tube, passing through the coil in the direction from the rear end towards the front end:
a second deflection coil of the saddle type also having a front end and a rear end for deflecting electron beams generated in the display tube in a horizontal direc-tion, as well as a yoke ring of ferromagnetic material sur-rounding the two deflection coils, which series is charact-erized in that the first and second deflection coils at their front ends have a cup-shaped portion which is adapted to the outer surface of the display tube, and at their rear ends have a cylindrical portion which is adapted to the sur-face of the display tube on the one hand the dimensions and the shape of the cup-shaped portion of the first deflection coils and on the other hand the shape and the dimensions of the cup-shaped portion of the second deflection coils in display tubes of different screen formats being the same, the effective length of the cylindrical portion of the first coil increasing and that of the second deflection coil decreasing when the screen format of the display tube for which they are mounted increases, and conversely.
(An example of a series of display tubes is, for example, a series having a constant deflection angle of 100 and 20, 22 and 26 inch screens).
As will be described in greater detail hereinafter with reference to the method of the invention, the great advantage of the invention is that for adaptation to the various screen formats of a given series, only a very small alteration in the length of the ~cylindrical) rear section of the individual deflection coils is necessary to obtain the desired variation in the distance between the deflection 63~
points. This means that the complicated cup-shaped portion may remain unvaried as regards dimensions so that self-con-verging deflection coils for display tubes of different screen formats can be made by means of one jig (having an adjustable rear section). In order to maintain convergence on the axes, the wire distribution in the cup-shaped portion of the coils needs at most only small alterations and in ; fact this applies only to the line coil. The main geometry, however, remains unchanged.
The invention therefore also relates to a method of assembling electromagnetic deflection units for colour display tubes of the in-line type having the same deflection angles and neck diameters but at least two different screen formats in which a first deflection coil of the saddle type having a front end and a rear end, a cup-shaped portion at the front end and a cylindrical portion at the rear end, for deflecting electron beams generated in the display tube in a vertical direction, the electron beams, when the deflection unit has been mounted on a display tube, passing through the coil in the direction from the rear end towards the front end, is combined with a second deflection coil, which coil ' is of the saddle type and has a front end and a rear end, a cup-shaped portion at its front end and a cylindrical por-tion at its rear end, for deflecting electron beams gener-ated in the display tube in a horizontal direction, a yoke ring of ferromagnetic material being provided around the assembly of the two deflection coils, characterized in that at least the second deflection coil is composed of two iden-tical halves which are wound on a jig having a cup-shaped portion and a cylindrical portion. The shape and the dimen-1~63Z`O
sions of the cup-shaped portion being the same for each screen format, the cylindrical portion of the jig, however, having an adjustable body for determining the length of the cylindrical portion of the coil halves.
A variation A D in the distance between line and field deflection point is produced by varying the effective length of the line coil with respect to that of the field coil. ~ D is linearly associated with the variation of the screen format, in which the relation applies that:
f~ D = ~ ~ Zs' where ~ Zs is the variation in the distance from the front end of the coil situated nearest to the screen (this gener-ally is the line coil) to the screen. The value of ~ is roughly between 0.05 and 0.15.
Embodiments of the invention will now be described in greater detail, by way of example, with reference to the accompanying drawing, in which:
Fig. 1 shows diagrammatically a colour display tube having a deflection unit;
Fig. 2 shows diagrammatically a deflection unit according to the invention suitable for a colour display tube having a first screen format;
Fig. 3 shows diagrammatically the same deflection unit as in Fig. 2 but now adapted to a colour display tube of a second screen format:
Fig. 4 shows diagrammatically a jig to be used in the method according to the invention and having an adjust-able rear section;
Fig. 5 is a side-elevation of a field coil half as used in the deflection unit shown in Fig. 2;
~r ~63;~
Fig. 6 is a side elevation of a field coil half as used in the deflection unit shown in Fig. 3;
Fig. 7 shows the magnetic fields generated in the axial direction by the deflection unit shown in Fig. 2;
Fig. 8 shows the magnetic fields generated in the axial direction by the deflection unit shown in Fig. 3.
Fig. 1 is a diagrammatic sectional view of a col-our display tube 1 of the in-line type having a display screen 2, a tube neck 3 and three electron guns 4 situated in one plane. A deflection unit 5 connected to the display tube comprises a rotationally symmetric yoke ring 6, a saddle coil 7 of the shell type for the horizontal deflection (the so-called line coil) and a saddle coil 8 of the shell type for the vertical deflection (the so-called field coil).
It has been found that, starting from a given main geometry of line and field coil, the variation of the effec- ;
tive lengths of the line coil and the field coil with res-pect to each other is a very helpful parameter to adjust the third order anisotropic astigmatism. The correction of the third order anisotropic astigmatism by mutual shifting of the deflection points is roughly ten times faster than by shifting the deflection unit as a whole.
It has so far geen generally believed that also in the construction of in-line deflection systems it was not allowed to deviate from the requirement accepted in the con-struction of delta deflection systems that line and field - deflection centres should coincide and should remain coin-ciding upon deflection. As will be explained hereinafter, the invention is based on the fact that in a deflection unit of the in-line type destined for use in combination with ~1;263~0 picture tubes having an tuninterrupted) line structure of the phosphors, the location of line and field deflection centres can just be optimalised in behalf of convergence and raster performance.
Of late years a development has occurred in colour television display systems which may be characterized by:
- the change of the delta arrangement of electron guns into an in-line arrangement in which the associated deflection system has been developed from non-self-converg-ing to self-converging;
- the change of the hexagonal mask structure of the display tube in to a line structure.
Where such a system must satisfy requirements as regards convergence, raster shape and purity (colour purity, landing reserve), requirements may be derived which each of : the components of said system should satisfy (think, for example, of the specific wire distribution for self-conver-gence).
Where purity is concerned, the general situation is that a deflection unit is given (which satisfies certain requirements as regards convergence, raster and shifting space), it being one of the responsibilities of the display tube designers to develop such an analogon of the electron-optical properties of said deflection unit that during the manufacture of the display screen the exposure optics ensure that the (visual) exposure "centre" and the deflection "centre" will afterwards coincide.
Because for a delta-gun arrangement coupled to a non-self-converging deflection unit the triodistortion (and the variation in deflection point~, upon deflection, results _ g _ 112~i3~
already in conflicting requirements to be imposed upon the exposure optics, a generally accepted requirement imposed from purity on the properties of the deflection unit is that in a delta system:
line and field deflection points should coincide and should go on coinciding upon deflection.
In in-line self-converging colour television dis-play systems the variation in deflection point of line and field coil is already so different in character that it was deemed necessary to abandon the hexagonal mask structure which was substantially ideal as regards purity properties t and to proceed to a line structure. Said line structure is characterized by a phosphor line which is uninterrupted in the field direction (which, with invisibility requirements imposed upon the mask structure remaining the same, has half the width of the original round phosphor dot).
These phosphor lines which are uninterrupted in the direction of the picture has the favourable result that in this direction in principle no mislanding (= not landing of a beam on a dot of its own coiour) can occur.
As a result of this, the differing variation in deflection point of the field coil with respect to the line coil can easily be permitted.
In that case it is in principle of no importance any longer for purity whether line and field deflection points will coincide also in the case of a deflection over a very small angle.
In other words, the generally accepted requirement in a delta system that in a deflection unit line and field deflection points will coincide and will go on coinciding ~.~;263~
upon deflection may be omitted in an in-line system when the hexagonal mask structure in the display tube is replaced by a line mask structure. (N.B.: so this is not a result of the in-line arrangement of the electron guns in themselves).
Within the scope of the invention this is used in the adaptation of the deflection unit 5 to a display tube having a screen 2' of a screen format different from that of the display screen 2 (in this case larger) but of equal deflection angle and neck diameter.
How this adaptation works is shown in more detail - in Figs. 2, 3, 4, 5 and 6.
Fig. 2 is a side elevation of the part of a deflection unit 9 situated above the tube axis and provided on a display tube 10. Deflection unit 9 comprises a line coil 11 having a front end 12 situated at a distance Zs from the display screen 13, and a field coil 14. In order that the deflection unit 9 be self-converging on the display tube lO (for example, a 110 tube having a 20 inch screen), the end 16 of the field deflection coil 14, as well as the end 15 of the line deflection coil 12 has a given length. The distance between the rear end 15 of the line deflection coil 12 and the rear end 16 of the field deflection coil 14 is denoted by S.
Fig. 3 shows a modified deflection unit 9', in this case the part situated below the tube axis, and shows that the distance S is changed into the distance S' where S' - S = S, by varying the lengths of the parts of the coils extending parallel to the tube axis. The deflection unit 9' is now self-converging on a display tube 17 having a second (larger) screen format (for example, a 110 tube hav-~i263~) P~ 9206 ing a 22 inch screen). In the present case the field deflec-tion coil 14 has for this purpose been extended on its rear side by approximately 5 mms and the line deflection coil 12' has been shortened on its rear side by approximately 5 mms, while the screen format is changed by 2 inches, which is shown in Fig. 3 by the distance ~ Zs by which the distance from the front end of the line deflection coil 12' to the display screen 18 has been increased from Zs to Zs' Changing the length of, for example, the field deflection coil is realised by means of a jig 19 which is shown in Fig. 4 diagrammatically partly as a plan view and partly as a sectional view. It consists of a (brass)lower jig 20 and a (brass) upper jig 21 which are separated from each other by a winding slot 22 where a winding wire is insorted. Holes to shoot pins into the rear end of a coil have been made in a cylindrical portion 23 which is screwed to the upper jig 21. One of these holes is denoted by 24.
These pins together with an exchangeable window block 25 screwed to the lower jig 20 determine the place where the copper wires bend on the rear side of the coil and hence determine the length of the deflection coil.
By placing a cylindrical auxiliary plate 26 of the required thickness between the upper ~ig 21 and the cylind-rical component 23 and simultaneously adapting the window block 25 as regards length, the jig can simply be made suit-able for winding another coil from the same family. The profiled member on the cup side which is difficult to manu-facture is not changed. Dies and winding wings need not be varied either. Preferably the lengths of the line and field deflection coils are varied in the opposite sense when ;
.~
~1~63~0 changing to another format, so that the differences between the coils from the whole family do not become too large (see also Fig. 2, 3).
Fig. 5 is a plan view of one half of the field deflection coil 27 and Fig. 6 is a plan view of one half of the field deflection coil 28 having an elongated rear end manufactured in the above-described manner.
By varying the distance between the rear ends of the line and field deflection coils, the distance between the line and field deflection point is varied and hence a deflection unit is obtained which is self-converging for another screen format. This is explained in Figs. 7 and 8.
A field deflection field HB and a line deflection field HL
are generated by means of a deflection unit as shown in Fig.
2. The field distribution measured in the direction of the axis of the display tube is as shown in Fig. 7. The maximum values of the two fields defining the Gauss deflection points are a distance D apart.
A field deflection field and a line deflection field having a field distribution as shown in Fig. 8 are generated by means of a deflection unit as shown in Fig. 3.
In this case the distance between the Gauss deflection points is D', with D' - D = ~ D.
For f~ D the relation holds that f~D = ~ ~ Zs~
25 where 0.05 C ~ ~ 0.15, and ~\ Zs (see Fig. 3) is the change in the distance between the front end of the line deflection coil and the screen when changing to a different screen for-mat.
X
A field deflection field and a line deflection field having a field distribution as shown in Fig. 8 are generated by means of a deflection unit as shown in Fig. 3.
In this case the distance between the Gauss deflection points is D', with D' - D = ~ D.
For f~ D the relation holds that f~D = ~ ~ Zs~
25 where 0.05 C ~ ~ 0.15, and ~\ Zs (see Fig. 3) is the change in the distance between the front end of the line deflection coil and the screen when changing to a different screen for-mat.
X
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A series of at least two electromagnetic deflec-tion units for colour display tubes of the in-line type having the same deflection angles and neck diameters but at least two different screen formats, in which each deflec-tion unit has:
a first deflection coil having a front end and a rear end for deflecting electron beams generated in the dis-play tube in a vertical direction, the electron beams, when the unit has been mounted on a display tube, passing through the coil in the direction from the rear end to the front end, a second deflection coil, which coil is of the saddle type and also has a front end and a rear end, for deflecting electron geams generated in the display tube in a horizontal direction, as well as a yoke ring of ferromagne-tic material surrounding at least the second deflection coil, characterized in that for a given screen format the first and the second coil each have a given effective length bet-ween their front and rear ends, the effective length of the first coil being larger and/or the effective length of the second coil being smaller for a larger screen format, and conversely, so as to provide for different screen formats a self-converging combination of display tube/deflection unit.
a first deflection coil having a front end and a rear end for deflecting electron beams generated in the dis-play tube in a vertical direction, the electron beams, when the unit has been mounted on a display tube, passing through the coil in the direction from the rear end to the front end, a second deflection coil, which coil is of the saddle type and also has a front end and a rear end, for deflecting electron geams generated in the display tube in a horizontal direction, as well as a yoke ring of ferromagne-tic material surrounding at least the second deflection coil, characterized in that for a given screen format the first and the second coil each have a given effective length bet-ween their front and rear ends, the effective length of the first coil being larger and/or the effective length of the second coil being smaller for a larger screen format, and conversely, so as to provide for different screen formats a self-converging combination of display tube/deflection unit.
2. A series of deflection units as claimed in Claim 1, characterized in that the deflection coils at their front ends have a cup-shaped portion and at their rear ends have a a cylindrical portion, the shape and the dimensions of the cup-shaped portion of the first deflection coils being equal for different screen formats and the shape and the dimens-ions of the cup-shaped portion of the second deflection coils being equal for different screen formats, the length of the cylindrical portion of the first coil increasing and/
or that of the second deflection coil decreasing when the screen format of the display tube increases, and conversely.
or that of the second deflection coil decreasing when the screen format of the display tube increases, and conversely.
3. A series of at least two combinations of display tube deflection unit, in which the display tubes have equal neck diameters and deflection angles but different screen formats and in which each deflection unit has:
a first deflection coil of the saddle type having a front end and a rear end for deflecting electron beams generated in the display tube in a vertical direction, the electron beams, when the deflection unit has been mounted on a display tube, passing through the coil in the direction from the rear end to the front end:
a second deflection coil of the saddle type, also having a front end and a rear end, for deflecting electron beams generated in the display tube in a horizontal direc-tion, as well as a yoke ring of ferromagnetic material sur-rounding the two deflection coils, characterized in that the first and second deflection coils at their front ends have a cup-shaped portion adapted to the outer surface of the dis-play tube and at their rear ends have a cylindrical portion adapted to the outer surface of the display tube, in which on the one hand the shape and dimensions of the cup-shaped portion of the first deflection coils in display tubes hav-ing different screen formats are the same and on the other hand the shape and dimensions of the cup-shaped portion of the second deflection coils in display tubes having differ-ent screen formats are the same, and in which the length of the cylindrical portion of the first coil increases and that of the second coil decreases when the screen format of the display tube on which they are mounted increases, and con-versely.
a first deflection coil of the saddle type having a front end and a rear end for deflecting electron beams generated in the display tube in a vertical direction, the electron beams, when the deflection unit has been mounted on a display tube, passing through the coil in the direction from the rear end to the front end:
a second deflection coil of the saddle type, also having a front end and a rear end, for deflecting electron beams generated in the display tube in a horizontal direc-tion, as well as a yoke ring of ferromagnetic material sur-rounding the two deflection coils, characterized in that the first and second deflection coils at their front ends have a cup-shaped portion adapted to the outer surface of the dis-play tube and at their rear ends have a cylindrical portion adapted to the outer surface of the display tube, in which on the one hand the shape and dimensions of the cup-shaped portion of the first deflection coils in display tubes hav-ing different screen formats are the same and on the other hand the shape and dimensions of the cup-shaped portion of the second deflection coils in display tubes having differ-ent screen formats are the same, and in which the length of the cylindrical portion of the first coil increases and that of the second coil decreases when the screen format of the display tube on which they are mounted increases, and con-versely.
4. A series of combinations of display tube deflec-tion unit as claimed in Claim 3, characterized in that the series comprises at least one combination of a display tube of a first screen format having a first deflection unit, in which the distance between the display screen and the front end of the deflection coil situated nearest to the display screen is Zs, and the distance between the deflection points of the fields generated by the deflection coils of the first deflection unit is D, and furthermore comprises at least one combination of a display tube of a second screen format with a second deflection unit, in which the distance between the display screen and the front end of the deflection coil of the second deflection unit situated nearest to the display screen is Z? and the distance between the deflection points of the fields generated by the deflection coils of the second deflection unit is D', where D - D' = .beta. (Zs - Zs'), and 0.05 < .beta. < 0.15.
5. A method of assembling electromagnetic deflection units for colour display tubes of the in-line type having the same deflection angles and neck diameters but at least two different screen formats in which a first deflection coil of the saddle type having a front end and a rear end, a cup-shaped portion at the front and a cylindrical portion at the rear end, for deflecting electron beams generated in the display tube in a vertical direction, the electron beams, when the deflection unit has been mounted on a display tube, passing through the coil in the direction from the rear end towards the front end, is combined with a second deflection coil, which coil is of the saddle type and has a front end and a rear end, a cup-shaped portion at its front end and a cylindrical portion at its rear end, for deflecting electron beams generated in the display tube in a horizontal direct-ion, a yoke ring of ferromagnetic material being provided around the assembly of the two deflection coils, character-ized in that at least the second deflection coil is com-posed of two identical halves which are wound on a jig hav-ing a cup-shaped portion and a cylindrical portion, the shape and the dimensions of the cup-shaped portion being the same for each screen format, the cylindrical portion of the jig, however, having an adjustable body for determining the length of the cylindrical portion of the coil halves.
6. A method as claimed in Claim 5, characterized in that the coil halves of the two deflection coils are wound on a jig having an adjustable body for determining the length of the cylindrical portion of the coil halves.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7808775 | 1978-08-25 | ||
| NLAANVRAGE7808775,A NL174198C (en) | 1978-08-25 | 1978-08-25 | SERIES OF AT LEAST TWO PICTURE TUBE / DEFLECTOR COMBINATIONS, DEFLECTION UNIT INTENDED FOR SUCH COMBINATION, AND METHOD FOR MANUFACTURING SUCH DEFLECTION. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1126320A true CA1126320A (en) | 1982-06-22 |
Family
ID=19831441
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA333,922A Expired CA1126320A (en) | 1978-08-25 | 1979-08-16 | Self-converging deflection units for colour display tubes of different screen formats |
Country Status (11)
| Country | Link |
|---|---|
| US (1) | US4272727A (en) |
| JP (1) | JPS5832893B2 (en) |
| CA (1) | CA1126320A (en) |
| DE (1) | DE2933945C2 (en) |
| ES (2) | ES483598A1 (en) |
| FR (1) | FR2434478A1 (en) |
| GB (1) | GB2029089B (en) |
| IT (1) | IT1162575B (en) |
| MX (1) | MX148378A (en) |
| NL (1) | NL174198C (en) |
| PT (1) | PT70108A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2534065A1 (en) * | 1982-10-05 | 1984-04-06 | Videocolor Sa | PROCESS FOR TRANSFORMING A DEVIATOR FOR ITS USE FOR TUBES WITH SELF-CONTAINING IMAGES OF DIFFERENT DIMENSIONS AND DEVIATOR THUS OBTAINED |
| NL8300729A (en) * | 1983-02-28 | 1984-09-17 | Philips Nv | DEVICE FOR DISPLAYING TELEVISION IMAGES AND DEFLECTOR THEREFOR. |
| NL8602407A (en) * | 1986-09-24 | 1988-04-18 | Philips Nv | ELECTROMAGNETIC DEFLECTOR. |
| NL8700835A (en) * | 1987-04-09 | 1988-11-01 | Philips Nv | DISPLAY DEVICE WITH PICTURE DEFLECTION COMBINATION. |
| NL8701276A (en) * | 1987-05-29 | 1988-12-16 | Philips Nv | IMAGE DISPLAY SYSTEM WITH DEFLECTOR WITH DOUBLE SADDLE REEL SYSTEM. |
| JPH0748359B2 (en) * | 1990-09-05 | 1995-05-24 | 東京特殊電線株式会社 | Deflection yoke |
| US20020172775A1 (en) * | 2000-10-24 | 2002-11-21 | Harry Buhay | Method of making coated articles and coated articles made thereby |
| JP2003031172A (en) * | 2001-07-16 | 2003-01-31 | Nikon Corp | Deflector and manufacturing method of the same, and charged particle exposing device |
| US7098584B2 (en) * | 2002-10-09 | 2006-08-29 | Matsushita Electric Industrial Co., Ltd. | Deflection yoke |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2882431A (en) * | 1956-11-13 | 1959-04-14 | Park Products Company | Self-convergent deflection yoke for a color tv cathode ray tube and system using the same |
| US3310763A (en) * | 1965-02-04 | 1967-03-21 | Rca Corp | Deflection yoke coil |
| JPS5230113A (en) * | 1975-09-02 | 1977-03-07 | Sony Corp | Deflecting device of in-line type color cathode-ray tube |
| NL7600687A (en) * | 1976-01-23 | 1977-07-26 | Philips Nv | DEFLECTION SYSTEM FOR A COLOR TELEVISION PICTURE TUBE. |
| JPS5942415B2 (en) * | 1976-01-26 | 1984-10-15 | ソニー株式会社 | In-line color cathode ray tube deflection device |
-
1978
- 1978-08-25 NL NLAANVRAGE7808775,A patent/NL174198C/en not_active IP Right Cessation
-
1979
- 1979-08-16 CA CA333,922A patent/CA1126320A/en not_active Expired
- 1979-08-21 US US06/068,371 patent/US4272727A/en not_active Expired - Lifetime
- 1979-08-21 MX MX179000A patent/MX148378A/en unknown
- 1979-08-22 FR FR7921168A patent/FR2434478A1/en active Granted
- 1979-08-22 DE DE2933945A patent/DE2933945C2/en not_active Expired
- 1979-08-22 IT IT25263/79A patent/IT1162575B/en active
- 1979-08-22 GB GB7929292A patent/GB2029089B/en not_active Expired
- 1979-08-23 ES ES483598A patent/ES483598A1/en not_active Expired
- 1979-08-23 PT PT70108A patent/PT70108A/en unknown
- 1979-08-23 ES ES483593A patent/ES483593A1/en not_active Expired
- 1979-08-24 JP JP54107336A patent/JPS5832893B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2933945A1 (en) | 1980-03-13 |
| NL174198B (en) | 1983-12-01 |
| NL174198C (en) | 1984-05-01 |
| JPS5530198A (en) | 1980-03-03 |
| NL7808775A (en) | 1980-02-27 |
| IT7925263A0 (en) | 1979-08-22 |
| PT70108A (en) | 1979-09-01 |
| GB2029089B (en) | 1982-08-25 |
| GB2029089A (en) | 1980-03-12 |
| US4272727A (en) | 1981-06-09 |
| FR2434478B1 (en) | 1982-03-05 |
| JPS5832893B2 (en) | 1983-07-15 |
| ES483598A1 (en) | 1980-09-01 |
| IT1162575B (en) | 1987-04-01 |
| FR2434478A1 (en) | 1980-03-21 |
| ES483593A1 (en) | 1980-04-01 |
| MX148378A (en) | 1983-04-13 |
| DE2933945C2 (en) | 1986-01-23 |
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| MKEX | Expiry |